Abstract The effect of sodium chloride on the diffusion of aqueous Na4ETRA (tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(ethyl)resorcin[4]arene) and Na4PRRA (tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(propyl)resorcin[4]arene) are investigated by using the Taylor dispersion technique to measure diffusion in… Click to show full abstract
Abstract The effect of sodium chloride on the diffusion of aqueous Na4ETRA (tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(ethyl)resorcin[4]arene) and Na4PRRA (tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(propyl)resorcin[4]arene) are investigated by using the Taylor dispersion technique to measure diffusion in aqueous resorcinarene solutions with and without added NaCl. In binary solutions of Na4ETRA or Na4PRRA (no added NaCl), the ETRA4− and PRRA4− ions diffuse at the same speed as the Na+ counterions to maintain electroneutrality. As a result, the binary diffusion coefficients of the resorcinarenes are weighted averages of the diffusion coefficients of the ETRA4− or PRRA4− ions and the relatively mobile Na+ ions. As the NaCl concentration is raised, the diffusion coefficients of Na4ETRA and Na4PRRA drop to the tracer diffusion coefficients of ETRA4− or PRRA4− ions in a supporting NaCl electrolyte solution. Coupled diffusion of Na4ETRA and Na4PRRA with NaCl is significant, driven primarily by the electric field (diffusion potential) generated by concentration gradients in Na4ETRA, Na4PRRA and NaCl.
               
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